Cooper's Hawk Guide (Accipiter cooperii)

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Aaron has been passionate about birds and nature since he was young. He has a Bachelor's in Environmental Science from the University of California Berkley and two master's degrees from the University of California, Davis, in Avian Science and Animal Behavior. Currently, he's a senior Environmental Scientist for the State of California. He is passionate about sharing his love of birds and making science and knowledge available to all.

Introduction / Taxonomy

The Cooper’s Hawk (Accipiter cooperii) is a species within the genus Accipiter. Accipiter is a group of raptors that includes 51 species found all around the world. Members of this genus are generally slender birds that have short, rounded wings and a long tail that serves as a rudder to help them maneuver. They have long legs and large feet with long, strong toes and sharp talons, which they use to capture and kill their prey. Members of this genus also have a sharp, hooked bill that is used in feeding.

Cooper’s Hawks are commonly found in a variety of habitats, including woodlands, shrublands, and urban areas. They often ambush their prey, which are generally small mammals and birds. They capture them after short, explosive flights. The typical flight pattern is a series of flaps followed by a short glide.

The Cooper’s Hawk females are approximately one-third larger than males.

The Cooper’s Hawk are an exclusively North American species with no populations, migratory routes, or portions of the species range on any other continent. The range of this species extends from southern Canada to northern Mexico. It has no recognized subspecies. However, there is a gradual change in body size from east (where birds are a bit smaller) to west (where birds are a bit larger). The Cooper’s Hawk is very closely related to the Bicolored Hawk of Central and South America and the Gundlach’s Hawk of Cuba.

Taxonomy at a Glance

Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformies
Family: Accipitridae
Genus: Accipiter
Species: cooperii

How to Identify a Cooper’s Hawk

Cooper’s Hawks are roughly crow-sized forest hawks. Their wings are relatively short and rounded. Their tails are long and rounded at the tip. They have tiny beaks and medium-sized eyes relative to the size of their blocky squared-off heads, which can sometimes display a slight crest. Their legs are long with large feet, long toes, and sharp talons.

Adult birds are blackish-blue on the crown of the head, show a rusty or orange-brown nape of the neck, and blue-grey on the back and on the upper surface of the wings. Adult bird’s have white undersides with horizontal, fine orange barring running across the breast and upper belly. They have fluffy white feathers near the lower belly and legs. Juvenile birds are brown on their backs, the top of their heads, and the face of their wings. Juvenile bird undersides are predominantly white. Dark brown streaks run vertically down the breast, where they are denser, and belly, where they become more scattered or even absent.

When in flight, Cooper’s Hawks beat their wings in a characteristic pattern of flap-flap-glide, flap-flap-glide.

Cooper’s Hawks Habitat

Cooper’s Hawks are very adaptable and live in a wide range of habitats. They generally prefer mixed and broadleaf forests, but they can be found in conifer forests, brushlands, wetlands, riparian areas, urban areas, and more. Cooper’s Hawks do tend to prefer edge habitats such as forest clearings, roadways, riverbanks, etc. Cooper’s Hawks have adapted to urban environments very well, with breeding populations established in many cities across the lower 48 states of the USA. Elevation ranges from sea level to about 3,000 meters.

Cooper’s Hawk Feeding Habits and Diet

This species of hawk eats predominantly other species of birds but will also eat mammals and very occasionally reptiles, amphibians, insects, and even fish when water levels are especially low. Bird prey species can range in size from small finches and warblers to large pigeons and doves and can even include small ducks. Cooper’s Hawks will sometimes raid the nests of other birds to take nestlings as food, particularly when Cooper’s Hawks are nesting. Foraging involves still hunting from a concealed perch, ambushing bird feeders and other common gathering sites of prey, or flights along the transition zones between habitats in the hopes of surprising prey.

This species generally hunts using a burst of sudden speed to surprise their prey. This surprise attack is generally followed by relatively short chase during which the hawk attempts capture its target before the animal escapes. Cooper’s Hawks are adaptable hunters and will pursue their prey in flight into dense cover, through urban landscapes, and even on foot.

Male birds, being smaller, tend to target smaller species of prey, while female birds, being larger, tend to target larger prey. This prevents the two members of a pair from competing with one another for prey. This way, they can maximize the number of prey deliveries and the diversity of prey species they are able to bring to their young during the breeding season.

Cooper’s Hawk Breeding

Breeding starts later in the year in northern regions and earlier in the year further south. In the northern USA and southernmost Canada, breeding begins in May-July. In the southern USA and northern Mexico, breeding can begin in February. Male Cooper’s Hawks establish territories and then display to attract a mate. These conspicuous displays include loud calling and circling flights to attract attention with slow, exaggeratedly deep, deliberate wing flaps.

Cooper’s Hawk Nesting

Nests are bulky platforms of sticks that are often lined with leaves and strips of bark. Nests are commonly built from eight to 20 meters above the ground at the point where a large branch forks or joins with the main trunk of a tree. Nest cups are generally shallower when built in a conifer tree and deeper when built in a broadleaf tree. Clutches range from three to six eggs but usually include from four to five eggs. Incubation lasts from 30 to 36 days and is conducted almost exclusively by the female bird. The male bird delivers food to the female, and while the female eats, the male will incubate the eggs briefly.

A baby hawk is known as an “eyas.” Eyas fledge from the nest about 27 to 34 days after they hatch, with the males generally fledging towards the earlier part of this range and females fledging towards the later part. Once fledged, the young birds usually remain in branches near the nest until they grow in all their feathers which generally takes another 15 to 20 days. Young at this stage of development are called “branchers.” They often return to the nest to rest until fully feathered.

Cooper’s Hawk Eggs

Eggs begin to be laid not long after the nest building is finished. One egg is laid at a time, usually with a day in between each egg. A complete Cooper’s Hawk clutch generally consists of three to five eggs. The eggs are similar in shape to chicken eggs but slightly smaller. They are usually pale blue to bluish-white and oval.

Cooper’s Hawk Population

Data collected by the North American Breeding Bird Survey, various migratory count sites, and the Christmas Bird Counts indicate that Cooper’s Hawk population numbers have increased dramatically since the 1970s, with particularly steep increases in the 1980s and 1990s. The most accurate population estimates are made from a combination of yearly migration counts across the range of this species and breeding population counts (particularly for counts in urban areas). The breeding population across North America is estimated to be between one hundred thousand and one million individuals.

Is the Cooper’s Hawk Endangered?

No. This species is of low conservation concern due to the significantly increasing population numbers that have been measured over the past several decades. Urban populations have been measured as growing and with higher density of nests than Cooper’s hawks breeding in more natural environments.

Like many other species of birds of prey, Cooper’s Hawks suffered dramatic breeding failure rates during the 1940s through the 1970s when the pesticide DDT and other organochlorine pesticides were in wide use in North America (declines were particularly significant in the eastern USA). The total population got so low that it was uncertain if this species would go extinct. Bans and restrictions on the use of these chemicals has resulted in population increases since the 1970s to the point where Cooper’s Hawks are now common sightings in most part of their range, although in Mexico the recovery has not been as strong as in the USA.

Cooper’s Hawk Habits

These hawks are found in a variety of habitats, but their hunting strategy is consistently one of ambushes. Once a potential prey is spotted, the hawk surges out of hiding in an explosive burst of high speed and high maneuverability flight. These chase flights usually do not last long, and either the hawk is successful, or the prey species eludes capture. Cooper’s Hawks do hunt birds at feeders, and the spread of backyard bird feeding may have helped populations of Cooper’s Hawks. In particular, bird feeders are a useful resource for urban living Cooper’s Hawks as they provide concentrations of prey species in urban landscapes that may otherwise have limited habitat for hunting.

When migrating, Cooper’s Hawks often loosely group together with individuals of other species of migrating birds of prey and also other Cooper’s Hawks, sometimes traveling in small groups of up to four birds.

Cooper’s Hawk Predators

Cooper’s Hawks are uncommonly eaten by larger hawks and owls such as Red-tailed Hawks, Goshawks, and Great Horned Owls. They can also be eaten by mammals such as raccoons. American Crows have been observed to rarely kill and eat Cooper’s Hawks.

Cooper’s Hawks used to be killed frequently by farmers trying to protect their chicken flocks from predation. This practice has largely stopped partly due to laws treaties being put in place that protect birds of prey and many other migratory birds that move within and between various countries. These include the Endangered Species Act in the USA and the Migratory Bird Treaty Act between Canada, the USA, and Mexico.

These laws and treaties have the specific goal of protecting many different bird species, including the Cooper’s Hawk.

Cooper’s Hawk Lifespan

Cooper’s Hawks tend to live an average of between 10 to 12 years in the wild. The oldest known wild Cooper’s Hawk lived to be at least 20 years and four months old. This bird was a male that was banded in California in 1986 and then found in Washington state in 2006.

FAQ

Question: Who was the Cooper’s Hawk named after?

Answer: The Cooper’s Hawk was named after a man named Willian Cooper, who was a New York ornithologist. It was named by another ornithologist, Charles Lucien Bonaparte, in 1828 after William Cooper. The two were friends, and William Cooper was the person who shot and collected the first examples of the species.

Question: How much weight can a Cooper’s Hawk carry in flight?

Answer: Cooper’s Hawks are quite strong. They can fly while carrying prey that is about twice their own body weight! For a female Cooper’s Hawk, this means they can carry prey that weighs up to four or five pounds.

Question: Do Cooper’s Hawks get hurt when chasing prey through trees and bushes?

Answer: Yes. Flying fast while chasing birds through dense foliage is very difficult and dangerous, and sometimes Cooper’s Hawks make mistakes and crash into a tree or bush. About twenty-three percent of Cooper’s Hawks that have been examined show signs of having broken and then healed bones and most of these breaks were in the bones chest and shoulders, suggesting that they were sustained during in-flight collisions. It is likely that injuries are actually even more frequent than this number suggests since many collisions are probably fatal.

Research Citations

Ferguson-Lees, J. and D. A. Christie. (2001). Raptors of the World. Houghton Mifflin Company, New York, NY, USA.

Johnsgard, P. A. (1990). Hawks, eagles, and falcons of North America. Smithsonian Institution Press, Washington D.C., USA.

Pyle, P. (1957). Identification Guide to North American Birds: a Compendium of Information on Identifying, Ageing, and Sexing “near-Passerines” and Passerines in the Hand. Slate Creek Press, Bolinas, CA, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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Cooper’s Hawk Guide (Accipiter cooperii)